/*========================== begin_copyright_notice ============================

Copyright (C) 2017-2021 Intel Corporation

SPDX-License-Identifier: MIT

============================= end_copyright_notice ===========================*/

#include "Compiler/Optimizer/OpenCLPasses/BreakdownIntrinsic/BreakdownIntrinsic.h"
#include "Compiler/IGCPassSupport.h"
#include "Compiler/CodeGenPublic.h"

#include "common/LLVMWarningsPush.hpp"
#include <llvm/IR/Function.h>
#include "common/LLVMWarningsPop.hpp"

using namespace llvm;
using namespace IGC;
using namespace IGC::IGCMD;

// Register pass to igc-opt
#define PASS_FLAG "breakdown-intrinsics"
#define PASS_DESCRIPTION "Breakdown intrinsics into simpler operations to enable better optimization"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS true
IGC_INITIALIZE_PASS_BEGIN(BreakdownIntrinsicPass, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_END(BreakdownIntrinsicPass, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)

char BreakdownIntrinsicPass::ID = 0;

BreakdownIntrinsicPass::BreakdownIntrinsicPass()
    : FunctionPass(ID), m_changed(false), m_pMdUtils(nullptr), modMD(nullptr) {
  initializeBreakdownIntrinsicPassPass(*PassRegistry::getPassRegistry());
}

void BreakdownIntrinsicPass::visitIntrinsicInst(llvm::IntrinsicInst &I) {
  // const MetaDataUtils &mdUtils = *(getAnalysis<MetaDataUtilsWrapper>().getMetaDataUtils());
  ModuleMetaData &modMD = *(getAnalysis<MetaDataUtilsWrapper>().getModuleMetaData());
  llvm::IRBuilder<> builder(&I);
  bool md_added = false;

  auto pCtx = getAnalysis<CodeGenContextWrapper>().getCodeGenContext();

  if (I.getIntrinsicID() == llvm::Intrinsic::fmuladd ||
      // For FMA only break it up if unsafe math optimizations are set
      (I.getIntrinsicID() == llvm::Intrinsic::fma && modMD.compOpt.UnsafeMathOptimizations)) {
    llvm::Value *pMulInst = builder.CreateFMul(I.getOperand(0), I.getOperand(1));
    llvm::Value *pAddInst = builder.CreateFAdd(pMulInst, I.getOperand(2));
    I.replaceAllUsesWith(pAddInst);
    I.eraseFromParent();
    m_changed = true;

    // The presence of fmuladd indicates that the fp_contract needs to be set.
    if (pCtx->m_DriverInfo.NeedsBreakdownMulAdd() && !md_added) {
      modMD.compOpt.MadEnable = true;
      md_added = true;
    }
  }
}

bool BreakdownIntrinsicPass::runOnFunction(llvm::Function &F) {
  m_pMdUtils = getAnalysis<MetaDataUtilsWrapper>().getMetaDataUtils();
  visit(F);
  return m_changed;
}
